11/09/2024 Additional validation for booking references (REST)

🐛 Bug Fix

A new rule BookingReference to validate contact requests with bookings

1. Booking reference gets rejected if it exists on another other account for the same provider

2. Booking reference gets accepted if it exists on this account,

3. Booking reference gets accepted if is is new.

4. Booking reference can be anything when no provider id is passed in

👩‍💻 Iris (developer) 👨‍💻 Tom D (reviewer)